Study of Stripe-shaped Optical Filter and Plasmonic Analogue of EIT Effect based on Hybrid Plasmonic Waveguides

Abstract: The rapid growth of nanotechnology leads to the possibility to fabricate ultra compact optical devices on a single chip. However, miniaturization of photonic circuits and devices is restricted by the diffraction limit. A promising solution to this problem is by exploiting plasmonic systems for guiding and manipulating signals at visible or communication wavelengths. Among different kinds of plasmonic waveguide, hybrid plasmonic (HP) waveguide shows a sub-wavelength confinement as well as long propagation distance, which has the potential to be applied in next-generation integrated circuits. This thesis is aimed to design optical devices based on HP waveguide, including optical filters and analogue of electromagnetically induced transparent (EIT) effect. The study methods are Scatter Matrix Method (SMM) and Finite Element Method (FEM) based simulation software, where SMM is used for calculate the numerical solutions of optical filter and FEM based simulation software is introduced to design, simulate and characterize the optical devices. We use the double-slot HP waveguide with metal cladding to realize the optical devices, which provide a good optical confinement. A stripe-shaped optical filter based on HP waveguide is designed and studied. The extinction ratio of the optical filter can be as low as 0.01 with a Q factor around 50. The analogue of EIT effect is also realized in this HP waveguide system, which is composed of double stripe-shaped resonators in form of resonant stubs with different lengths located on each side of the HP waveguide. At two resonant frequencies (150THz and 222THz) resonance is obtained in respective stub, where the transmittance can be as low as 0.01. In the frequency range of 150THz and 222THz, a constructive interference is obtained between the two resonant stubs, where a maximum transmittance occurs, which can be as high as 0.7 at the frequency of 184THz (λ=1.63μm). Accompanying with the transparency ‘window’, the group veloc ity can be slowed down as much as 30 times in respect to the velocity of light in vacuum.